Learning systematic practices can challenge traditions, but a small Ohio molder sees promise. Endura Plastics Inc. has scored improvements since development engineer Haans Petruschke attended General Polymers-sponsored seminars on systematic molding strategies in June and July.
``He has implemented this technology with some good success stories,'' said John Bozzelli, senior technical consultant.
Changes takes time.
``The old notion has been that injection pressure and injection speed are separate entities,'' Petruschke said. ``This is not the case. Velocity or speed control is achieved by allowing hydraulic pressure to vary. This has been a difficult concept to get across.''
Melt viscosity variations are compensated for by changes in hydraulic pressure — more for stiffer resin and less for easier flowing resin — Bozzelli said, ``Something like cruise control on a car.''
Mark DiLillo, Endura president, has supported the gradual transition, asking employees to try scientific molding. On key jobs in recent months, Endura:
Equalized the fill pressure in a four-cavity mold to correct the flatness of a rejected part made with a 15-percent-glass-filled polybutylene terepthalate, and reduced the 40-second cycle by one second in fill time and seven seconds in cooling time, a 20 percent improvement.
Optimized the fill time of a mounting pan made with 30-percent-glass-filled modified poly-phenylene oxide in a four-cavity hot runner mold. The change reduced cycle time by four seconds, packed out the part properly and corrected the flashing over of a precision 0.016-inch bleed hole.
Improved an engine control module bracket of polyetherimide on an eight-cavity hot runner mold. Cycle time was cut 1.3 seconds without adverse effects on quality or process-capability ratio.
Endura has used three to six hours of machine time per study and a total of 100 hours on various experiments over five months.
``We hope to make the study standard operating procedure in the future,'' Petruschke said.
The company hired a process engineer to boost the effort.
Specializing in high-temperature thermoplastics, Endura injection molds precision high-volume components on 12 Newbury, four Battenfeld, three Van Dorn and one Autojector injection molding presses with clamping forces of 40-275 tons at its plant in Kirtland, Ohio. Also, the firm provides engineering and design services, builds molds, does insert molding, assembles and decorates.
The company was founded in 1966, employs 80, produces parts largely for under-the-hood automotive applications and reported 1995 sales of $5.6 million.
General Polymers is a division of Ashland Chemicals Co., a unit of energy and chemical firm Ashland Inc. of Russell, Ky. General Polymers has 20 North American sales offices and distribution locations.